This invention relates to pyrometer systems for gas-turbine engines.
Measuring the temperature of rotating blades in a gas-turbine engine can be carried out by means of a pyrometer system which analyses the radiation emitted by the blades and from this obtains a measurement of the blade temperature. One problem with these systems is that radiation produced as a result of burning fuel in the combustion chamber may enter the pyrometer, either directly or by reflection from the moving or stationary components of the engine. Unless this extraneous radiation, or the signals it produces in the pyrometer system are removed, it can lead to errors in the measurement of temperature. Attempts to remove the effects of the flame signal are made more difficult by the fact that the system may be required to respond to an anomalously high signal such as produced by an overheated blade.